Micrometer comprising a digital counter

ABSTRACT

Micrometer comprises a spindle which is axially advanced by rotating a knob or ring and a digital indicating counter actuated in response to movement of said spindle and seated in the guide for said spindle. The micrometer comprises means for adjusting the counter and means for taking up any play between the spindle and spindle guide.

United States Patent Nakata Sept. 18, 1973 MICROMETER COMPRISING ADIGITAL COUNTER [75] Inventor: Kiyohiro Nakata, Kure, Japan [73]Assignee: Yehan Numata, Yokohama City,

Japan [22] Filed: May 1, 1972 [21] Appl. No.2 249,277

[30] Foreign Application Priority Data May 11, 1971 Japan 46/3764) [52]US. Cl. 33/166 [51] Int. Cl. G0lb 3/18 [58] Field of Search 33/166 [56]References Cited UNITED STATES PATENTS 3,120,061 2/1964 Pfleiderer33/166 3,340,616 9/1967 Mincuzzi 33/166 FOREIGN PATENTS OR APPLICATIONS20,771 0/1909 Great Britain 33/166 Primary ExaminerHarry N. HaroianAttorneyJoseph F. Brisebois et a1.

[57] ABSTRACT Micrometer comprises a spindle which is axially advancedby rotating a knob or ring and a digital indicating counter actuated inresponse to movement of said spindle and seated in the guide for saidspindle. The micrometer comprises means for adjusting the counter andmeans for taking up any play between the spindle and spindle guide.

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MICROMI'ITER COMPRISING A DIGITAL COUNTER SUMMARY OF THE INVENTION Thisinvention relates to a micrometer comprising a digital counter whichindicates in large numerals the value measured by the micrometer, whichvalue is also indicated by a scale on the micrometer spindle.

It is an object of the invention to provide such a micrometer in whichany longitudinal error caused by thrust during rotation of the spindleis eliminated by suitable take-up means eliminating axial play betweenthe spindle and the main body of the micrometer.

It is a further object of the invention to provide means for adjustingthe value indicated by the counter for a given axial position of thespindle.

Other objects of the invention will become apparent from a reading ofthe following description of a preferred embodiment of the invention,with reference to the accompanying drawings, in which:

FIG. 1 is a side view, partially in axial section, showing oneembodiment of the micrometer according to the invention; and

FIG. 2 is a sectional view, taken along the line ll-ll of FIG. 1.

Referring now to FIG. 1, reference numeral 34 indicates a knob fixed toa screw 34A, screwed into the internally threaded part 8A of a hollowspindle 8. The left end of the screw 34A has left-handed threads, sothat the.knob and spindle turn as an integral unit. A collar 27encircles the end of the part 8A of the spindle and is rigidly connectedto the part 8A so as to rotate therewith. A eap 29 is gripped betweenthe collar 27 and knob 34.

On the collar 27 are screwed a nut 23 having an inwardly projectingflange 23A and a nut 28 covered by the cap 29.

A plurality of balls 24 are seated in an annular groove in the member20, which forms part of the main stationary body of the micrometer. Theflange 23A engages one side of these balls, while the ring 25, on theother side of these balls is spaced from the collar 27 by the spring 26.It will be appreciated that this arrangement permits the spindle 8 andcollar 27 to rotate freely with respect to the body 20, while the actionof the spring prevents any relative axial movement therebetween, sincethe flange 23A and 25 act as jaws gripping the balls to prevent suchaxial movement.

A knurled ring 41 is held on the nut 23 by a set screw 30, so that thenut 23, collar 27 and spindle 8 may be rotated by the ring 41. The ring41 comprises a ring gear 22, the internally projecting teeth of whichengage a pinion 21 mounted on a shaft 19 journalled in the body part 20.Rotation of the ring 41 thus turns the pinion 21, the shaft 19, and thepinion 18 at the other end of the shaft 19. The pinion l8 drives a gear16, rotatably mounted on the part 83 of the spindle 8. The gear 16 isintegral with member which drives the first wheel 40A of a counter 40.The subsequent wheels 40B, 40C, and 40D of this counter are drivensuccessively in a conventional manner, with each wheel being turnedthrough one-tenth of a revolution each time the preceding wheelcompletes a full revolution. A window 42, through which the numbers onthe wheels may be viewed, is provided in the main body 1 of themicrometer. An auxiliary or vernier scale may be attached to the ringgear 22 and cooperate with an index on the main body.

The left end of the spindle 8 is externally threaded and encircled by asleeve 6 fixed to the feeler 2. As best seen in FIG. 2, the feeler 2 isprovided with a longitudinal external groove which receives the end of akey screw seated in the main body. The arrangement is such that rotationof the spindle 8 causes the feeler 2 to slide axially in the main body,since relative rotation therebetween is prevented by engagement of thetip of the keyscrew 32 in the longitudinal groove in the feeler 2.

Rotation of the spindle is produced by rotation of either the knob 34 orthe knurled ring 41, and such rotation results in corresponding rotationof the wheels of the counter, as previously described.

If it becomes necessary to adjust the position of the counter wheelswhich corresponds to a particular position of the spindle and feeler,the screw 30 is loosened. This permits the nut 23 and ring gear 22 to berotated about the spindle 8, while driving the counter wheels throughthe gears 22, 19 and 20, until the desired relative position isattained. The set screw 30 may then be tightened again.

What is claimed is:

1. In a micrometer comprising a main body (20), an elongated feeler (2)axially slidable within said body, elongated rotatable means (34, 8, 23,27, 28, 29) for axially sliding said feeler with respect to said body,and a counter (40) connected to indicate changes in the position of saidfeeler relative to said body, the improvement which comprises:

resilient means (26) biassing said rotable means to a constantlongitudinal position relative to said main body,

a gear (22) carried by said rotatable means and connected to drive saidcounter when there is relative movement between said rotatable means andsaid main body, and

means (30) operable from outside said micrometer to separably fastensaid gear to said rotatable means, so that said gear may be unfastenedfrom said rotatable means and actuated to change the indication given bysaid counter without rotating said rotatable means.

2. A micrometer as claimed in claim 1 comprising ball bearing means (24)seated in said body and jaws (23A, 25) carried by said body and grippingsaid bearing means, one of said jaws (25) being movable longitudinallyof said rotatable means and biassed toward said bearing means by saidresilient means.

i t i fi

1. In a micrometer comprising a main body (20), an elongated feeler (2)axially slidable within said body, elongated rotatable means (34, 8, 23,27, 28, 29) for axially sliding said feeler with respect to said body,and a counter (40) connected to indicate changes in the position of saidfeeler relative to said body, the improvement which comprises: resilientmeans (26) biassing said rotable means to a constant longitudinalposition relative to said main body, a gear (22) carried by saidrotatable means and connected to drive said counter when there isrelative movement between said rotatable means and said main body, andmeans (30) operable from outside said micrometer to separably fastensaid gear to said rotatable means, so that said gear may be unfastenedfrom said rotatable means and actuated to change the indication given bysaid counter without rotating said rotatable means.
 2. A micrometer asclaimed in claim 1 comprising ball bearing means (24) seated in saidbody and jaws (23A, 25) carried by said body and gripping said bearingmeans, one of said jaws (25) being movable longitudinally of saidrotatable means and biassed toward said bearing means by said resilientmeans.